Superthin absorbent product

ABSTRACT

A superthin absorbent disposable product is provided having an absorbing layer containing superabsorbent and a wicking layer. The product is suitable for use in disposable diapers, sanitary napkins, incontinent pads, wipes and the like.

BACKGROUND OF THE INVENTION

The present invention relates to new and improved absorbent productsand, more particularly, to new and improved thin absorbent compositesincorporating superabsorbent materials.

Disposable absorbent products have been known for some time, includingsuch products as disposable diapers, sanitary napkins, wound dressings,bandages, incontinent pads, and the like. These products incorporate anabsorbent batt which is used to absorb and hold or contain body fluids.Initially, in many of these products, especially diapers and sanitarynapkins, the absorbent batt comprised what is termed "wadding" or pliesof tissue. The wadding was disposed between an impermeable backing and apermeable facing and the plies of tissue were used to absorb and,hopefully, contain the liquid within the product. A diaper whichutilizes such an absorbent batt is disclosed in U.S. Pat. Re. No.26,151.

The wadding type of batt was replaced, for the most part, by an improvedabsorbent batt which comprises what is termed "fluffed wood pulpfibers". This absorbent batt comprises a layer of individualized woodpulp fibers with the layer having substantial thickness. A diaper whichincorporates such a fluffed wood pulp absorbent batt is described inU.S. Pat. No. 2,788,003. This diaper had improved absorbent capacity andsomewhat better containment than a diaper using a wadding layer. Alsothe fluffed wood pulp layer is quite soft, flexible and conformable andhence, produces an improved diaper over diapers using wadding as theabsorbent layer.

Though the fluffed wood pulp absorbent batts have improved capacity, theefficiency with which the capacity is used in a diaper or sanitarynapkin is poor. The reason for this, is that the fluid to be absorbed isgenerally deposited in a localized area within the absorbent batt andthe ability for the fluid to move along the plane of the batt is poor.The fluid follows the path of least resistance and consequently moves tothe closest edge of the batt where it generally is no longer containedand the product leaks.

U.S. Pat. No. 3,017,304 discloses an absorbent product whichincorporates in the product a densified, paper-like layer. Thispaper-like layer acts as a wick, i.e., liquid which is placed on thelayer tends to move rapidly along the plane of the layer. Whenincorporated in combination with fluffed wood pulp fiber, the resultantproduct uses the absorbent capacity of the fluffed wood pulp much moreefficiently. Diapers which incorporate this paper-like layer combinedwith fluffed wood pulp are disclosed and described in U.S. Pat. Nos.3,612,055 and 3,938,522. This concept of combining a wicking orcapillary skin or layer with fluffed wood pulp fibers has gained wideacceptance in many absorbent products including disposable diapers andsanitary napkins. Even though these products make much greater use ofthe capacity of the absorbent batt, they still do not totally containthe absorbed liquid. It is probable that these products will leak beforethe full capacity of the batt is used for absorption. This is especiallytrue if pressure is placed on the batt while wet, for example a babysitting down on a previously wetted diaper will very often cause thebatt to leak.

Recently, elastic leg diapers or stretch diapers have been introducedinto the marketplace. Though these diapers provide no better absorbentbatt than flat diapers or the prior art diapers, they have indicatedimproved containment of liquid. Such diapers are disclosed and describedin U.S. Pat. Nos. 3,860,003, 4,050,462, and 4,324,245. Though thecontainment features are better than the prior art products, theelasticized products fit more tightly permitting less air circulation.Frequently, this can become irritating to the skin and the tighter theelastic or the more close fitting the diaper, the greater theirritation. This is especially true adjacent the area where the elasticleg portion of the product contacts the wearer.

A number of years ago "superabsorbent materials", i.e., materials whichwill absorb many times their weight of liquid, were developed. Since thedevelopment of such materials, people have been trying to incorporatethem in absorbent products such as diapers and sanitary napkins toenhance the absorptive performance of these products. Theoretically, aminimum amount of superabsorbent incorporated in a product would makethat product perform as well or better than the prior art products.Perhaps one of the first products to incorporate such a superabsorbentmaterial in a disposable diaper is disclosed in U.S. Pat. No. 3,670,731.This patent discloses an absorbent dressing comprising an absorbentlayer sandwiched between a permeable facing and an impermeable backingsheet. The absorbent layer contains water insoluble cross-linkedhydrocolloid polymer as the superabsorbent material.

Even though superabsorbent materials have been available for some time,they have not gained wide acceptance in absorbent products such asdisposable diapers and sanitary napkins. A primary reason for this lackof acceptance of the superabsorbents is failure to develop a productcapable of economically utilizing the highly increased absorptivecapacity of the superabsorbent material. In order to economicallyutilize a superabsorbent, the liquid being absorbed must be transportedto the superabsorbent material. In other words, the superabsorbentmaterial must be placed in contact with the liquid. Furthermore, as thesuperabsorbent material absorbs the liquid, it must be allowed to swell.If the superabsorbent is prevented from swelling, it will ceaseabsorbing liquid. Hence if the superabsorbent material is to function indiapers and sanitary napkins wherein the liquid to be absorbed is placedin a small void area, the structure of the absorbent layer containingsuperabsorbent materials appears to be critical. Over the years a numberof techniques have been disclosed in an attempt to provide structureswhich make efficient use of the superabsorbent material. Such productsare disclosed in U.S. Pat. Nos. 4,103,062, 4,102,340, and 4,235,237. Inaddition, methods for incorporating superabsorbents into suitable layersor suitable configurations which can be placed in an absorbent product,are disclosed in U.S. Pat. Nos. 4,186,165 and 4,340,057. To date, noneof these products has met with any substantial commercial success.

The present invention provides a new and improved absorbent compositewhich utilizes a substantial portion of the absorptive capacity ofsuperabsorbent materials. This new composite makes use of this capacityeven though the liquid being absorbed is placed on the composite in alocalized area. Furthermore and unexpectedly, the new absorbentcomposite maintains a desired softness, flexibility, and conformabilitywhile efficiently using the superabsorbent material thereby making itespecially suitable for use in disposable diapers. In addition andunexpectedly, the new composite contains the liquid absorbed in thecomposite even without the use of elastic leg members in the product.Surprisingly, the new composite will contain absorbed liquid even whenpressure is placed upon the product during use.

SUMMARY OF THE INVENTION

The present invention provides a disposable absorbent, compressedcomposite comprising an absorbing layer, a transition area, and awicking layer. The absorbing layer is comprised of a fibrous web havinga dry bulk recovery of at least about 60 percent, an initial dry bulk ofat least about 20 cc/gm and a weight of less than about 2 oz/yd² (68gm/m²). The absorbing layer has superabsorbent material in the form of aplurality of particles or globules of superabsorbent material disposedin a random and intermittent arrangement throughout the absorbing layer.The particles or globules are of a size and spacing so that they do notinterfere with the absorption of liquid by adjacent particles. Thewicking layer is comprised of particles which are cellulosic fibers,peat moss, or mixtures thereof. These particles are randomly disposed,frictionally entangled and sufficiently closely spaced to adjacentparticles to assist in promoting rapid movement of liquid along theplane of the layer. The transition area is comprised of portions of theentangled particles of the wicking layer extending into and becomingintegral with the absorbing layer. Some portions of the wicking layerparticles are in intimate contact with some of the superabsorbentmaterial. The compressed composite, in its compressed form, is less thanone-half its thickness in an uncompressed form and upon contact withliquid regains at least 75 percent of its thickness in uncompressedform.

The absorbent system of the present invention is comprised of at leasttwo layers to form a thin, absorbent structure. One layer functionsprimarily as a liquid transport media, i.e., a wicking layer. The otherlayer functions as an absorbent reservoir to retain volumes of bodyfluids. This layer is referred to as the absorbing layer. The absorbinglayer is a low density, resilient, fibrous web consisting of randomlydisposed, frictionally entangled fibers which result in a web having adry bulk recovery of at least 60 percent, an initial dry bulk of atleast 20 cc/gm and a weight less than about 2 oz/yd². The fibrous webmaking up the absorbing layer is used to spacially distributesuperabsorbent material so that upon exposure to an aqueous fluid,swelling occurs with minimal interference from adjacent superabsorbentmaterial. The transporting or wicking layer is a high density structuremade of particles selected from the group consisting of cellulosicfibers, peak moss, or mixtures thereof. One layer is superimposed uponthe other by air laying with or without vacuum, water casting or thelike. The two layers are compressed at a pressure adequate to collapsethe total structure to promote intimate contact between the wickinglayer and the absorbing layer. In fact, at least portions of some of theparticles of the wicking layer extend into and become integral with theabsorbing layer providing a transition area wherein some of theparticles come in contact with some of the superabsorbent materialinterspersed in the absorbing layer. Generally, the compression iscarried out in the presence of a moisture content of at least about 10percent so that some of the superabsorbent is soft and tacky and uponcompression holds the absorbing layer in a compressed state. When beingused, the compressed composite product is exposed to a fluid includingbody fluids such as urine, menstrual fluid, or other fluids. Generally,the fluids are deposited in a localized area on one surface of thecompressed composite product. The wicking layer immediately transportsany excess fluid in any given area to other areas in the x,y plane ofthe layered structure. As fluid contacts the unwetted areas of thestructure, the superabsorbent in intimate contact with the wicking layerbegins to form a gel and soften. As softening occurs, the absorbinglayer is gradually released from its compressed state and recoverssubstantially its original low density nature due to the fibrous webresilience. This low density provides storage areas for the liquid andthe superabsorbent continues to swell with minimal interference fromadjacent superabsorbent material. As the liquid front moves along the x,y plane, it triggers sequential release of the resilient structure toallow fluid migration in the z direction as well, i.e., in the directionof the thickness of the product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating one embodiment of the presentinvention;

FIG. 2 is an enlarged cross-sectional view through lines 2--2 of FIG. 1;

FIG. 2A is an enlarged cross-sectional view through lines 2--2 of FIG. 1but after compression;

FIG. 3 is a perspective view illustrating another embodiment of thepresent invention;

FIG. 4 is a perspective view illustrating still another embodiment ofthe present invention;

FIG. 5 is an enlarged cross-sectional view through lines 5--5 of FIG. 4;

FIG. 6 is a perspective view of a blank for a tampon embodying thepresent invention;

FIG. 7 is a perspective view of a tampon made from the blank shown isFIG. 6;

FIG. 8 is a perspective view of another blank for a tampon embodying thepresent invention;

FIG. 9 is a cross-sectional view of a tampon made from the blank of FIG.8; and

FIG. 10 is a perspective view of a wipe illustrating another embodimentof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, FIG. 1 represents a perspective view ofan absorbent product of the present invention. The absorbent product 10has a fibrous web as an absorbing layer 12. Interspersed and fixed inthe absorbing layer are superabsorbent particles 16. Immediatelyassociated with the absorbing layer is the wicking layer 14. Some of theparticles of the wicking layer 14 extend into and become integral withthe absorbing layer 12 thus forming the transition area 18. Thestructure depicted in FIG. 1 is in an uncompressed state for ease ofillustration. Upon compression some of the particles in the wickinglayer 14 will extend into and become integral with the fibers of theabsorbing layer. These wicking layer particles consequently will also bein contact with the superabsorbent particles. Generally at least 10percent moisture is present when the structure is compressed under apressure sufficient to compact the structure and cause the softenedsurface of the superabsorbent material to provide the necessary adhesionto the fibers with absorbing layer so that they remain in a compactedstate.

FIG. 2 provides a cross-sectional view along line 2--2 of FIG. 1 showingin detail the relationship of the layers of the absorbent product. Theabsorbing layer 22 is made from resilient fibers. The superabsorbentparticles 24 are interspersed and fixed among the resilient fibers 23.The wicking layer 28 is comprised of particles 26 some of which extendinto and become integral with the absorbing layer. The transition area25 contains the wicking layer particles 26 in contact with a portion ofthe wicking layer 28 so as to be in intimate contact with some of thesuperabsorbent particles 24. FIG. 2A depicts the structure of FIG. 2 ina compressed state showing that the absorbing layer 23A has beensubstantially reduced in thickness and the wicking layer 28A has alsobeen reduced in thickness but extends considerably into and becomesintegral with the absorbing layer to form the transition area 25A.Although the superabsorbent particles 24A are closer to each other,there is still sufficient opportunity for liquid to pass between theparticles and upon their softening, the resilient fibers of theabsorbing layer are released to return the layer to its original lowdensity form.

Referring now to FIG. 3, a diaper 30 is depicted. A moisture-perviousfacing such as a nonwoven fabric 31 provides the diaper surface. Amoisture-impervious substance, such as polyethylene, forms themoisture-proof backing 32 of the diaper. This particular diaperstructure 30 contains one complete compressed composite layer, 33, andtwo layers, 34 and 35, which are placed only in the front portion of thediaper, each layer being the absorbent structure shown in FIG. 1, but ina compressed state. In order to seal the diaper in the margins, gluelines 38 are provided. To secure the diaper about the waist of thewearer, tape tabs 39 are provided. The diaper product 30 provides anexceptionally thin diaper which accepts liquid and rapidly transports itto all areas of the absorbent structures 33, 34, and 35. In producing adiaper in accordance with FIG. 3, one or more layers of the absorbentstructure may be used. Generally, the wicking layer is placed closest tothe facing. However, when multiple composites are being used, theremaining composites may be placed with the wicking layer either towardthe facing or the backing. Even using three layers of the absorbentstructure of the present invention a diaper is provided having lessthickness than a commercial fluff pulp diaper presently available.

Referring now to FIG. 4, a sanitary napkin 40 is provided having afabric overlay 42. FIG. 5 is a cross sectional view along line 5--5 ofFIG. 4 showing the layer construction in the napkin depicted in FIG. 4.The structure 50 has a moisture-permeable nonwoven fabric 52.Surrounding the sides and bottom area of the structure is amoisture-impermeable wrap 54. Immediately associated with the exteriorwrap 52 in the fluid receiving area is an absorbent structure 55 with awicking layer 56 in immediate contact with the exterior wrap. Thus, asthe liquid enters the absorbent structure 55 through the exterior wrap52 it is immediately transported in the wicking layer 56. The liquidthen migrates through the absorbing layer 57 and into the adjacentabsorbing layer 59 of absorbent structure 53. As the liquid continuesits progression throughout the entire structure 50, it proceeds towicking layer 51 of absorbent structure 53 and is transported in the x,yplane along the moisture-impermeable wrap 54. The two compressedcomposite structures 53 and 55 provide a sanitary napkin of less thanhalf the thickness of the conventional fibrous batt napkin.

FIG. 6 depicts a blank 60 for manufacturing a tampon consisting of asingle absorbent structure depicted in FIG. 1 but in a compressed state.The surface 64 is the surface of the absorbing layer and is a nonwovenfabric of wet-resilient fibers having interspersed thereinsuperabsorbent. The surface 62 is a layer of wood pulp fibers closelyassociated with the absorbing layer. The two layers are in a compressedstate resulting in a transition area 63. The blank 60 is rolled andshaped so as to form the tampon 70 depicted in FIG. 7. The broken awayportion of the drawing shows the absorbing layer 74 and the wickinglayer 72 and the transition area 73.

In still another tampon structure depicted in FIG. 8, a blank 80 isprovided with a wicking layer 81, an absorbing layer 83, and anotherwicking layer 82 on the opposite surface of the absorbing layer. Thisstructure provides to transition areas 85 and 86 upon compression.Superabsorbent particles 84 are interspersed and fixed in the absorbinglayer 83. The tampon blank 80 is folded over and shaped to provide thetampon 90 in FIG. 9. In FIG. 9 the tampon is cut away to provide across-sectional view showing the two wicking layers 91 and 92 with theabsorbing layer 93 sandwiched in between. The absorbing layer containsthe superabsorbent particles 94. Transition areas 95 and 96 provide thenecessary contact of the wicking layer particles with the absorbinglayer superabsorbent material.

FIG. 10 depicts a wipe 100 wherein a polypropylene nonwoven fabric 102forms a substrate. Affixed to the substrate 102 is a compressedcomposite 104 with its absorbing layer superimposed on the substrate 102and the wicking layer forming the opposing surface.

These and other products such as incontinent pads, wound dressings, andthe like may be made from the absorbent structure depicted in FIG. 1 butin a compressed state.

The absorbing layer is a fibrous web generally formed from syntheticstaple fibers such as polyethylene, polypropylene, polyester, nylon, andthe like. However, cellulosic fibers such as rayon may be used. Thefibrous web has a dry bulk recovery of at least about 60 percent, aninitial dry bulk of at least about 20 cc/gm and a weight of less thanabout 2 oz/yd². The resulting resiliency of the fibrous web permits theabsorbing layer to regain at least 75 percent of its original thicknesswhen it is released from its compressed state as liquid penetrates theabsorbent product. The fibrous web may be formed by dry laying or wetlaying fibers but in such a manner as to provide the necessary lowdensity structure. In one embodiment, staple polyester fibers areair-laid to form a web which web is subsequently lightly bonded bypassing hot air through the fibers in order to provide some degree ofintegrity to the web structure.

The superabsorbent material present in an intermittently dispersed formin the absorbing layer is generally a water-insoluble butwater-swellable polymeric substance capable of absorbing water in anamount which is at least 10 times the weight of the substance in its dryform. The superabsorbent material is in the form of particles which maybe in the shape of fibers, spheres, bits of film, or the like, or may beapplied in the form of a liquid monomer which is subsequentlypolymerized. Generally, the polymerized liquid monomer provides globulesand bits of film-like particles in the structure.

The particles or fibers may be described chemically as having a backboneof natural or synthetic polymers with hydrophyllic groups or polymerscontaining hydrophyllic groups being chemically bonded to the backboneor an intimate admixture therewith. Included in this case of materialsare such modified natural and regenerated polymers as polysaccharidesincluding, for example, cellulose and starch and regenerated cellulosewhich are modified by being carboxyalkylated, phosphonoalkylated,sulphoalkylated or phosphorylated to render them highly hydrophyllic.Such modified polymers may also be cross-linked to enhance theirhydrophyllicity and render them water-insoluble.

These same polysaccharides may also serve, for example, as the backboneonto which other polymer moieties may be bonded by graftcopolymerization techniques. Such grafted polysaccharides and theirmethod of manufacture are described in U.S. Pat. No. 4,105,033 toChatterjee et al. and may be described as polysaccharide chains havinggrafted thereon a hydrophyllic chain of the general formula ##STR1##wherein A and B are selected from the group consisting of --OR³, --O(alkali metal), --OHNH₃, --NH₂, wherein R¹, R² and R³ are selected fromthe group consisting of hydrogen and alkyl having 1 to 4 carbon atoms,wherein r is an integer having a value of 0 to about 5000, s is aninteger having a value of 0 to about 5000, r plus s is at least 500, pis an integer having a value of zero or 1 and q is an integer having avalue of 1 to 4. The preferred hydrophyllic chains are hydrolyzedpolyacrylonitrile chains and copolymers of polyacrylamide and sodiumpolyacrylate.

In addition to modified natural and regenerated polymers, thehydrocolloid particle component may comprise wholly synthetichydrophyllic particles. Examples of those now known in the art arepolyacrylonitrile fibers which may be modified by grafting moietiesthereon such as polyvinyl alcohol chains, polyvinyl alcohol itself,hydrophyllic polyurethane, poly(alkyl phosphonates), partiallyhydrolyzed polyacrylamides (e.g., poly(n-N-Dimethyl acrylamide),sulfonated polystyrene, or poly(alkylene oxide). These highlyhydrophyllic synthetic polymers may be modified by other chemicaltreatments such as cross-linking or hydrolysis. Further examples knownin the art are the non-ionic hydrophyllic polymers such aspolyoxyethylene, polyoxypropylene and mixtures thereof which have beensuitably cross-linked, either chemically or with radiation. Stillanother more recent type is a derivative of isobutylene-maleic anhydridecopolymer.

Hydrophyllic polymers formed from water-soluble acrylate monomers, suchas sodium, potassium, ammonium (or combination of cations), acrylate,may be placed on the absorbing layer by spraying or otherwise placing asolution thereon followed by polymerization and cross-linking, forexample, by irradiation.

Any superabsorbent which absorbs large amounts of liquids is suitablefor use in the absorbing layer of the present invention.

The wicking layer is comprised of cellulosic fibers, peat moss, ormixtures thereof. These cellulosic fibers include wood pulp fibers,cotton linters, and the like. The wood pulp fibers generally are thosethat are used to form the fluff or fibrous batt layer in conventionalabsorbent products such as disposable diapers, sanitary napkins, etc.Other cellulosic fibers that might be used are rayon fibers, flax, hemp,jute, ramie, cotton and the like. The fibers or peat moss or mixturesthereof are placed in such a way as to form a layer in which theparticles are immediately adjacent one another so as to promote wickingof liquid in the plane of the layer.

The wicking layer can be preformed and placed next to the absorbinglayer before compression or the wicking layer particles can be air-laidor wet-laid on to the absorbing layer before compression.

The transition area is a region formed at the junction of the absorbinglayer and the wicking layer. Some of the particles of the wicking layerextend into and become integral with the absorbing layer. The region inwhich the majority of the extending particles lie is identified as thetransition area. In the transition area, there is a composite ofabsorbing layer fibers, superabsorbent material, and wicking layerparticles. The wicking layer particles which have extended into theabsorbing layer are in intimate contact with some of the superabsorbentmaterial of the absorbing layer. This permits the liquid to commence itsmigration in the z direction to reach the superabsorbent material. Asthe liquid progresses in the z direction, the superabsorbent materialbecomes soft and releases the absorbing layer fibers which permit theabsorbing layer to return to at least 75 percent of its uncompressedthickness. As the absorbing layer returns to its uncompressed thickness,larger void areas are provided for storage of the liquid and forincreased swelling of the superabsorbent material as it absorbs theliquid residing in the void areas.

In order for the absorbing layer fibrous web to provide the necessarymedium for absorbing liquid, the fibrous web has a dry bulk recovery ofat least 60 percent, an initial dry bulk of at least about 20 cc/gm, anda weight of less than about 2 oz/yd². The initial dry bulk is the areatimes thickness of the layer under a load of 0.01 pounds per square inchcalculated in cubic centimeters. This value is divided by the weight ingrams in order to provide the measurement in cubic centimeters per gram.The dry bulk recovery is obtained by subjecting the web to a load of1.75 psi for five minutes, removing the load and allowing the web torest for one minute, subjecting the web to a load of 0.01 psi for oneminute and then measure the final dry bulk. The dry bulk recovery is thefinal bulk divided by the initial bulk expressed in percent. If thefibrous web can provide this dry bulk recovery and has an initial drybulk of at least 20 cc/gm with a web weight of less than 2 oz/yd², thefibrous web will meet the requirements of the absorbing layer. When thefibrous web has these requirements, it can retain superabsorbentmaterial up to at least 1,500 percent of the dry basis weight of theweb. It is preferable that the web contain 200 percent to 1,500 percentby weight dry basis superabsorbent to the dry basis weight of the web.Most preferred is a range from about 400 percent to about 1,200 percent.

Examples of methods of preparing the absorbent product of the presentinvention are as follows. These examples are not intended to be limitingin any way and extensions and modifications thereof without departurefrom the spirit and scope of the invention will become apparent fromthese examples.

EXAMPLE 1

An absorbing layer is formed by polyester fibers by dry laying thefibers, i.e., by air laying or carding to form a web. The web is thensubjected to heat bonding to provide integrity to the web. The resultingweb is 25 grams per square meter, basis weight. The specific polyesterfibers used are identified as Type 99 Hollofil fibers manufactured andsold by E. I. Dupont Company. The fibrous web is placed on top of asheet of wet-formed chemically delignified wood pulp fibers, the fibersbeing identified as RayFloc JLD manufactured by ITT Rayonair having abasis weight of 50 grams per square meter. A powder superabsorbentpolymer is uniformly sprinkled onto and into the nonwoven fiberpolyester structure at a concentration of 200 grams per square meter.The particular superabsorbent used is identified as Permasorb 10manufactured by National Starch and Chemical Corporation. The structureis sprayed with a mist of water on the polyester side and then subjectedto a compression force of 640 psi for 30 seconds. On release of thepressure the structure remains compressed and is available to functionas an absorbent product described in this invention.

EXAMPLE 2

Using the same polyester fibrous web formed in Example 1, the web iscoated by flooding it with an aqueous solution of 38% solids, thesolution solids being 90% sodium acrylate and 10% acrylic acid. Vacuumin the amount of one inch of mercury is used to withdraw the excesssolution from the web. The web is then subjected to 6 megarads ofelectron beam radiation. The web is again flooded subjected to vacuumand irradiated. A third time after flooding and the vacuum treatment,the web is subjected to 12 megarads of electron beam radiation topolymerize and crosslink the monomer and form polysodium acrylate (PSA)affixed to the polyester fiber. Two hundred grams/m² of PSA is presentin the substrate. This is equivalent to 800% dry-add-on. This coatedsubstrate is passed beneath a hammer mill that deposits chemicallytreated wood pulp fibers onto the polyester web. Vacuum is applied underthe polyester web so as to cause some of the pulp fibers to at leastpartially migrate into the polyester web and become integral therewith.The major portion of the wood pulp fibers will reside on the surfaceproviding a layer containing wood pulp fibers of 50 gms/m². The surfaceof the pulp layer is sprayed with water so that the total moisturecontent of the pulp is 10 percent by weight. This structure iscompressed at a level of 640 psi for 30 seconds. Upon release ofpressure the pulp has formed into a high density layer with a capillarysize suitable for liquid wicking and the resilient fiber layer remainscompressed. Upon use of this structure when liquid contacts the surfaceand migration of the liquid into the product takes place, thesuperabsorbent become soft and releases the resilient fibers so that thethickness of the absorbent structure increases markedly. This providesan area for storage of liquid wherein the capillary size is large.

EXAMPLE 3

The same polyester web is treated with a wood pulp fiber-water slurrywhich is drained through the polyester fiber web so that a pulp depositof 50 grams per square meter is formed on one side of the polyester web.The two layered sheet is dried. Onto the polyester web side of the sheetis sprayed the same monomer solution as in Example 1, so thatpractically no monomer solution contacts the wood pulp fiber layer. Asbefore, the sample is coated and treated three times providing 800%dry-add-on of PSA. The resulting structure at a moisture content ofapproximately 50 percent by weight is compressed at a level of 640 psifor 30 seconds. Upon release of the pressure the structure remainscompressed and is ready for use as taught hereinbefore.

When placing the superabsorbent into the absorbing layer, it isimportant that the superabsorbent be in the proper quantity andadequately spaced so that gel blocking does not take place. Gel blockingoccurs when superabsorbent is in sufficient quantity or the particlesare sufficiently close together that as they swell a layer of gel isformed and additional liquid cannot penetrate that layer.

The moisture layer of the two layers prior to compression preferably issufficient to make the exterior surface of the superabsorbent tacky soas to provide a temporary bonding of the wet resilient fibers undercompression. Thus, the compressed composite structure remains compresseduntil it is in contact with sufficient liquid for the superabsorbent tobegin swelling and to thereby release the bonds formed with theresilient fibers.

The structure is compressed sufficiently to reduce the thickness of thestructure by at least 50 percent and the pressure must be sufficient tocause the composite to remain compact after the pressure is released.

Other methods for preparing the absorbent product of the presentinvention may be used.

From the foregoing it will be observed that numerous variations andmodifications may be effected without departing from the true spirit andscope of the novel concept of this invention.

We claim:
 1. A disposable absorbent compressed composite laminatecomprising a first layer, a second layer, and a transition areaintegrally and intimately connecting said first and second layers andbeing substantially coextensive therewith, said first layer comprising afibrous web having a dry bulk recovery of at least about 60 percent, aninitial dry bulk of at least about 20 cc/gm, and a weight less thanabout 2 oz/yd², and a plurality of particles or globules ofsuperabsorbent material disposed randomly and intermittently throughoutsaid first layer, said particles or globules being of a size and spacingwhereby said particles do not interfere with the absorption of liquid byadjacent particles, said second layer comprising randomly disposed,frictionally entangled particles selected from the group consisting ofcellulosic fibers, peat moss, and mixtures thereof, said particles beingsufficiently closely spaced to adjacent particles to promote rapidmovement of liquid along the plane of said layer, and said transitionarea comprising portions of said entangled particles extending into andbecoming integral with said first layer with portions of said entangledparticles in intimate contact with said superabsorbent material, saidcomposite laminate in its compressed form being less than one-half itsthickness in an uncompressed form and upon contact with liquid, regainsat least 75 percent of its thickness in uncompressed form.
 2. Thecompressed composite laminate of claim 1 wherein said first layer is anonwoven fabric of synthetic staple fibers.
 3. The compressed compositeof claim 2 wherein the nonwoven fabric is polyester.
 4. The compressedcomposite laminate of claim 1 wherein said second layer is chemicallydelignified wood pulp fibers.
 5. The compressed composite laminate ofclaim 1 wherein said second layer is peat moss.
 6. The compressedcomposite laminate of claim 1 wherein the superabsorbent material ispresent in an amount from about 200 percent to about 1,500 percent bydry weight based on the dry weight of said fibrous web.
 7. A disposableabsorbent compressed composite comprising an absorbing layer, atransition area, and a wicking layer, said absorbing layer comprising afibrous web having a dry bulk recovery of at least about 60 percent, aninitial dry bulk of at least about 20 cc/gm, and a weight of less thanabout 2 oz/yd², said wicking layer comprising particles selected fromthe group consisting of cellulosic fibers, peat moss, and mixturesthereof, some of said particles extending into and becoming integralwith said absorbing layer to provide said transition area, saidabsorbing layer having interspersed therein superabsorbent materialarranged so as not to gel block and present in an amount between about200 percent and 1,500 percent dry weight basis based on said fibrous webdry weight basis, said composite in its compressed form being less thanone-half its thickness in an uncompressed form and upon contact withliquid regains at least 75 percent of its thickness in uncompressedform.
 8. The compressed composite of claim 7 wherein said absorbinglayer is a nonwoven fabric of synthetic staple fibers.
 9. The compressedcomposite of claim 8 wherein the nonwoven fabric is polyester.
 10. Thecompressed composite of claim 7 wherein said wicking layer is chemicallydelignified wood pulp fibers.
 11. The compressed composite of claim 7wherein said wicking layer is peat moss.
 12. The compressed composite ofclaim 7 wherein said superabsorbent is present in an amount from about400 percent to about 1,200 percent dry weight basis based on saidfibrous web dry weight basis.
 13. A disposable diaper containing anabsorbent pad wherein said absorbent pad is an absorbent compressedcomposite comprising an absorbing layer, a transition area, and awicking layer, said absorbing layer comprising a fibrous web having adry bulk recovery of at least about 60 percent, an initial dry bulk ofat least about 20 cc/gm, and a weight of less than about 2 oz/yd², saidwicking layer comprising particles selected from the group consisting ofcellulosic fibers, peat moss, and mixtures thereof, some of saidparticles extending into and becoming integral with said absorbing layerto provide said transition area, said absorbing layer havinginterspersed therein superabsorbent material arranged so as not to gelblock and present in an amount between about 200 percent and 1,500percent dry weight basis based on said fibrous web dry weight basis,said composite in its compressed form being less than one-half itsthickness in an uncompressed form and upon contact with liquid regainsat least 75 percent of its thickness in uncompressed form.
 14. Thedisposable diaper of claim 13 wherein said absorbent pad is comprised oftwo or more absorbent compressed composites.
 15. The disposable diaperof claim 13 wherein the absorbing layer of said compressed composite iscomprised of a polyester nonwoven web and the wicking layer of saidcompressed composite is comprised of chemically delignified wood pulpfibers.
 16. The disposable diaper of claim 13 wherein said compressedcomposite is comprised of an absorbing layer sandwiched between twowicking layers.
 17. A sanitary napkin comprising an absorbent structurepartially encompassed by a liquid barrier with a moisture-permeableoverwrap, said absorbent structure being a disposable absorbentcompressed composite laminate comprising a first layer, a second layer,and a transition area integrally and intimately connecting said firstand second layers and being substantially coextensive therewith, saidfirst layer comprising a fibrous web having a dry bulk recovery of atleast about 60 percent, an initial dry bulk of at least about 20 cc/gm,and a weight less than about 2 oz/yd², and a plurality of particles orglobules of superabsorbent material disposed randomly and intermittentlythroughout said first layer, said particles or globules being of a sizeand spacing whereby said particles do not interfere with the absorptionof liquid by adjacent particles, said second layer comprising randomlydisposed frictionally entangled particles selected from the groupconsisting of cellulosic fibers, peat moss, and mixtures thereof, saidparticles being sufficiently closely spaced to adjacent particles topromote rapid movement of liquid along the plane of said layer, and saidtransition area comprising portions of said entangled particlesextending into and becoming integral with said first layer with portionsof said entangled particles in intimate contact with said superabsorbentmaterial, said composite laminate in its compressed form being less thanone-half its thickness in an uncompressed form and upon contact withliquid, regains at least 75 percent of its thickness in uncompressedform.
 18. The sanitary napkin of claim 17 wherein said absorbentstructure comprises two compressed composite laminates superimposed oneupon the other with the absorbing layers immediately adjacent oneanother.
 19. A tampon having as its absorbent portion a disposableabsorbent compressed composite laminate comprising a disposableabsorbent compressed composite laminate comprising a first layer, asecond layer, and a transition area integrally and intimately connectingsaid first and second layers and being substantially coextensivetherewith, said first layer comprising a fibrous web having a dry bulkrecovery of at least about 60 percent, an initial dry bulk of at leastabout 20 cc/gm, and a weight less than about 2 oz/yd², and a pluralityof particles or globules of superabsorbent material disposed randomlyand intermittently throughout said first layer, said particles orglobules being of a size and spacing whereby said particles do notinterfere with the absorption of liquid by adjacent particles, saidsecond layer comprising randomly disposed frictionally entangledparticles selected from the group consisting of cellulosic fibers, peatmoss, and mixtures thereof, said particles being sufficiently closelyspaced to adjacent particles to promote rapid movement of liquid alongthe plane of said layer, and said transition area comprising portions ofsaid entangled particles extending into and becoming integral with saidfirst layer with portions of said entangled particles in intimatecontact with said superabsorbent material, said composite laminate inits compressed form being less than one-half its thickness in anuncompressed form and upon contact with liquid, regains at least 75percent of its thickness in uncompressed form.
 20. The tampon of claim19 wherein said compressed composite laminate is comprised of twowicking layers one on each side of an absorbing layer.
 21. A wipecomprising a nonwoven fabric as a substrate having affixed thereto adisposable absorbent compressed composite laminate comprising a firstlayer, a second layer, and a transition area integrally and intimatelyconnecting said first and second layers and being substantiallycoextensive therewith, said first layer comprising a fibrous web havinga dry bulk recovery of at least about 60 percent, an initial dry bulk ofat least about 20 cc/gm, and a weight less than about 2 oz/yd², and aplurality of particles or globules of superabsorbent material disposedrandomly and intermittently throughout said first layer, said particlesor globules being of a size and spacing whereby said particles do notinterfere with the absorption of liquid by adjacent particles, saidsecond layer comprising randomly disposed frictionally entangledparticles selected from the group consisting of cellulosic fibers, peatmoss, and mixtures thereof, said particles being sufficiently closelyspaced to adjacent particles to promote rapid movement of liquid alongthe plane of said layer, and said transition area comprising portions ofsaid entangled particles extending into and becoming integral with saidfirst layer with portions of said entangled particles in intimatecontact with said superabsorbent material, said composite laminate inits compressed form being less than one-half its thickness in anuncompressed form and upon contact with liquid, regains at least 75percent of its thickness in uncompressed form.